1. Field of the Invention
The present subject matter is directed to a method and device for relieving a pressure within a first cavity to a second cavity in a subsea facility.
2. Description of the Related Art
There are several wireline and well control functions that require occasional pressure testing and/or pressure build-up monitoring to assure that barriers and seals are functioning properly during installation and workover operations. Typically, this involves a test line conduit that can either supply pressurized fluids to the testing location or allow the venting and removal of fluids for leak detection. However, operations associated with light well intervention (RLWI) often adopt a philosophy of “no hydrocarbons to surface.” In other words, the conduit between the test location and the pressure/monitor source is no longer present due to the possibility of wellbore fluids (hydrocarbons) traveling through the conduit to the pressure/monitor source on the vessel in proximity to personnel. If the conduit is present, more safety measures and higher vessel certification are required in order to properly handle and dispose of hydrocarbons should they become present. All of this, in turn, increases the day rate (charges per day) which would otherwise make RLWI less economical.
FIG. 1 is an exemplary schematic drawing showing an illustrative prior art RLWI system where the subject matter disclosed herein may be employed. As will be recognized by those skilled in the art after a complete reading of the present application, the system depicted in FIG. 1 is only an example, as the subject matter disclosed herein may be employed with any subsea system where such features are desirable.
FIG. 1 shows a subsea lubricator stack 10 for an intervention system attached to a subsea well 5 equipped with a Christmas tree 6 and a flowline/umbilical 7 extending to a process facility (not shown). The subsea lubricator stack 10 includes a pressure control device such as a Lower Riser Package (LRP) 11, a lubricator (pipe) 12 and the pressure control head (PCH) 13. The system has a control unit 15 for the control of the various processes during the operation. A special intervention umbilical 17 may be attached to the control unit 15. The umbilical 17 extends to a remote control station (not shown). The line 23 may carry electrical and/or optical signals and hydraulic lines for fluid communication between the control unit 15 and devices in the PCH 13. The lubricator stack 10 is used to insert tools into the well as is well known in the art.
The present invention is directed to methods and devices solving, or at least reducing the effects of, some or all of the aforementioned problems.